The verification device of the low-concentration dust concentration measuring instrument is like a rigorous referee, meticulously testing the accuracy of the dust concentration. Its existence, like a guardian, ensures the accuracy of the measuring instruments and escorts our environmental monitoring work. Compared with similar projects at home and abroad, the "low-concentration dust concentration measuring instrument verification device" realizes the closed-loop control of the whole process, the system structure is reasonable, the dust used meets the requirements of relevant standards, the uniformity and stability of the device powder feeding are guaranteed, and the technical level has reached the domestic level.
Dust samplers and dust concentration measuring instruments are widely used in many aspects, such as air quality testing, as well as the air pollution situation announced by the environmental protection department, as well as the evaluation of whether environmental protection policies and measures are effective, all need the data of dust samplers and dust concentration measuring instruments as a basis. But the dust sampler can not get the measurement result directly, and the dust concentration can be obtained by using other equipment to carry out the secondary test and convert on the basis of the dust sampler measurement, so that the measurement step is cumbersome, and the error is relatively large, and it is very inconvenient in the actual production application. The direct-reading dust concentration measuring instrument can directly measure the measured dust concentration, with high accuracy, easy operation, and saves a lot of experimental steps, so the direct-reading dust concentration measuring instrument is gradually replacing the dust sampler.
However, the direct-reading dust concentration measuring instrument is a new measuring instrument in recent years, and the calibration methods used by the manufacturer before the instrument leaves the factory are different, which makes the response curve and accuracy of the instrument inconsistent, which leads to a very large difference in the mass concentration measurement in the same environment. At present, whether at home or abroad, there is no forming or excellent performance of the dust meter verification device. There are foreign application equipment in this area, which is expensive and cannot be accurately controlled. Most of the domestic use is still part of the imported powder equipment and other equipment domestic, the two are built, and the closed loop of the whole test process has not yet been formed, and the system structure is not very reasonable, and the individual device is difficult to meet the requirements of the relevant standards due to the limitations of its powder feeding mechanism, so that the test principle is very different from the actual use of the dust concentration measuring instrument.
Based on the premise of the actual use environment, the design plan was determined. The simulated dust concentration measuring instrument is composed of the main parts such as the micro powder feeding system, the induced air filtration system, the dust dilution unit, the diffusion unit, the detection unit and the dust collection unit. The basic principle is to introduce the external air into the device through the filter, and at the same time use the dust conveyor of the micro powder feeder (with static elimination function) to send the dust to the induced air pipe and mix with the clean air to form a dust aerosol, and then use the stirring blades to further dilute and neutralize the dust aerosol, so that the dust particles are evenly distributed in the air and then slowly enter the detection chamber through the diffusion section, so that the dust particles of small particle size form a resuspension state, and the reference dust concentration meter (or filter membrane sampler) The dust concentration is collected and detected at the same time as the tested dust concentration meter, and then the verification results are obtained by comparison; The dust that is not collected by the dust concentration measuring instrument (or filter sampler) enters the dust collector and is adsorbed by the filter element, and the clean air is discharged through the induced draft fan. It not only satisfies the needs of the tested measuring instrument and the transmission of the value, but also ensures the reliability and accuracy of the comparison and detection results.
In the solution of key problems, grasp the key of uniform powder feeding of dust generator to ensure the reliability and accuracy of experimental data, and the micro powder feeding system developed has the characteristics of adjustable powder feeding, high powder feeding stability and long continuous working time. The powder feeding system has the following characteristics: first, the air volume of powder output can be adjusted; Second, the grading system has a cleaning function, which can be self-cleaned, so as to avoid dust deposition or adsorption in the pipeline; Third, the vacuum generation part is equipped with an electrostatic eliminator, which can well isolate noise. Moreover, the project team will further optimize the experimental parameters and equipment according to the problems found in the actual application, and further improve the uniformity and stability of the powder feeding of the device.
After a long period of efforts, we have developed a multi-generation verification device that can meet the requirements of JJG846-2015 "Dust Concentration Measuring Instrument" metrological verification instrument, and has the conditions for establishing the environment, personnel and equipment standards for low-concentration dust meter verification devices, and solves the problem of traceability of dust concentration tester.
The verification device of the low concentration dust concentration measuring instrument is equipped with an advanced data processing system, which can process and analyze the measurement data in real time, which further improves the accuracy and reliability of the measurement. At the same time, the device can also automatically correct and compensate the data according to different measurement requirements to ensure the reliability of the measurement results.
The verification device of the low-concentration dust concentration measuring instrument also has the characteristics of simple operation and easy maintenance. It adopts a user-friendly operation interface and intelligent control software, which makes it easy for users to carry out measurements and calibration. At the same time, the device also has good durability and stability, and can work stably for a long time under various complex environmental conditions.
The verification device of low-concentration dust concentration measuring instrument is a powerful and stable precision equipment, which can provide a reliable guarantee for the measurement and calibration of low-concentration dust. It can be widely used in environmental protection, health and epidemic prevention, occupational disease prevention and other fields, and plays an important role in ensuring people's health and environmental safety.